The present invention relates to privacy apparatus for telephone systems, and more particularly pertains to exclusion circuits located at subscriber sets, wherein the first subscriber in a talk circuit loop to go off-hook excludes all other subscribers from becoming connected to that talk loop.
In the field of privacy exclusion it has been the practice to employ a separate and additional means at each subscriber key set to activate and deactivate an exclusion feature. The present invention employs the line and hold button switches normally present at all key sets for this purpose. When prior art exclusion circuits are being deactivated in order to permit a third party access they must hold down the deactivating switch until the third party joins the line. Normally the exclusion circuits of the prior art require a separate signalling device to indicate to the user that his exclusion circuit is either operating or inactive. The present invention utilizes the light under the hold button of the key set for such purpose, thereby eliminating the requirement of an extra indicator. Generally, prior art exclusion circuits are complicated and expensive. The exlusion apparatus of the present invention is compact and relatively inexpensive.